This invention relates generally to blanks formed of cardboard or similar carton stock material that can be assembled readily into packages and containers for various goods, and more particularly relates to improvements that facilitate handling, assembly and use of such blanks.
Carton blanks, of the type comprising a unitary flat sheet of cardboard carton stock having various pre-marked lines formed thereon in a predetermined pattern that allows the blank to be bent and/or folded from its planar flat stage into a three-dimensional structure having the shape of a carton or box-like container, are well-known. It is also well known that the same carton shape, having a slightly different shape and/or different dimensions can be provided to serve as a telescopically engageable lid or cover for open-sided carton containers of the type herein described. The terms carton, container and the like, as used in this specification, should be understood as being used interchangeably and collectively to identify both containers and/or covers. In this art, flat carton blanks are commonly identified by the initials or monogram, KDF, derived from the first letters of the words in the identifying phrase, xe2x80x9cknocked down flatxe2x80x9d.
KDF blanks characterized by pre-defined patterns of crease and/or fold lines that permit the blank to be bent and folded readily into a three-dimensional structure having the shape of a container with three or more upright sidewalls surrounding a base portion, have been known and used for many years. Such blanks frequently include various forms of tabs and flaps that can be brought into overlapping relationship and then secured together so as to retain the desired finished shape. In the prior art, the overlapping tabs and flaps of KDF blanks have been fastened together mechanically as by staples, and by applying liquid adhesives to one or both of two appropriate opposed abutting surface portions, and then allowing the adhesive to xe2x80x9csetxe2x80x9d so as to assure that the surfaces are attached to each other. Proper application of the adhesive, to assure both correct positioning of the adhesive on the respective overlapping portions, and controlled application of the proper quantity of adhesive for proper fastening strength, is a difficult and labor-intensive process that cannot be performed readily or conveniently in the field.
As an alternative to field assembly, it is known that KDF blanks can be formed and then assembled in a manufacturing plant under carefully controlled conditions, so that completely formed and assembled containers and mating covers can be shipped to end users in finished form, ready to be used without further handling other than packing and closing. However, this method of selling and distributing containers for goods has the serious disadvantage of adding substantial expense to the final cost of the finished product, because the containers generally cannot be nested or otherwise compressed in volume for shipping. As a direct result of the difference between the volume occupied by a stack containing a given number of container blanks and the volume occupied by an equal number of assembled containers, shipping costs for a given quantity of assembled containers are substantially higher than for the same quantity of blanks.
Another problem represented by the prior art technology of KDF containers relates to storage and handling of the flat blanks from which containers are formed. It is common in this art to print information and/or designs on the side of the KDF blank that will form the outer surface of the assembled container. The characteristics of the printing materials, such as inks, that are widely used for this purpose are such that the blanks tend to stick to each other when they are stacked in tiered relationship after they have been printed. Separating stored blanks that have become stuck together often requires additional time and effort in handling, and the separation process may result in the loss of any number of blanks due to damage caused by adhesion, all of which can add significant cost to the final product.
Still further, and independently of the adhesion caused by the printing materials, it is known that the accumulated weight of a stack of tiered blanks can cause compression that is sufficient to exclude all or substantially all of the air from between the abutting surfaces of adjacent blanks; exclusion of air in this manner can result in the formation of a vacuum that has the effect of sealing of adjacent, abutting blanks to each other. A vacuum formed in this manner can have the effect of slowing the processing of individual blanks because of the time and significant effort that may be required to xe2x80x9cbreakxe2x80x9d the vacuum so that adjoining blanks can be separated from each other.
Although clinging together of adjacent blanks caused either by printing materials or by vacuum sealing usually can be overcome by manual handling of the blanks, the required time and labor tend to add significant cost to the final product. Any increase in cost, however slight, can have a serious adverse effect on the success of a product in an industry such as this, where cost is a particularly important element of commercial success.
Accordingly, it is an object of this invention to provide an improved container blank that can be shipped as a blank singly or in stacked bundles and can be assembled easily, conveniently and accurately in the field.
It is another object of this invention to provide a container blank that can be fastened together easily in final form without requiring the use of mechanical fasteners or handling of liquid adhesives.
It is still another object of this invention to provide a KDF container blank that can be separated easily and conveniently when blanks are stored in closely packed stacked relationship.
These and other and further objects, features and advantages of this invention will be made apparent to those having skill in this art by reference to the following specification in the context of the accompanying drawings, in which: